1、RECOMMENDATION ITU-R BT. 1369 BASIC PRINCIPLES FOR A WORLDWIDE COMMON FAMILY OF SYSTEMS FOR THE PROVISION OF INTERACTIVE TELEVISION SERVICES (Question ITU-R 232/1 i) (1 998) This Recommendation is based on a draft prepared by Study Group 11 in 1996. This draft was refined in conjunction with the ITU
2、-T Study Group 9. It gives general guidance for the harmonious development of interactive television services. It covers the subject areas of interaction channels, interactive services and transport mechanisms. To maintain consistency with ITU-T, it is reproduced below in a form identical to ITU Sta
3、ndardization Sector Recommendation J. 1 1 O. BASIC PRINCIPLES FOR A WORLDWIDE COMMON FAMILY OF SYSTEMS FOR THE PROVISION OF INTERACTIVE TELEVISION SERVICES Summary This Recommendation, which has been produced in conjunction with the broadcasting study groups of the Radiocommunication Sector of the I
4、TU, gives general guidance for the harmonious development of interactive television services. It covers the subject areas of interaction channels, interactive services and transport mechanisms. 1 Introduction The development of new digital technology has led to the convergence of broadcasting, telec
5、ommunications and computers. There has been rapid progress towards enhanced digital television broadcasting using HFC, SMATV, MMDS, LMDS, ISDN, ADSL, terrestrial over-air transmission, satellite delivery systems, etc. Reliance upon digital technology provides opportunities for the introduction of in
6、teractive services. Interactivity may be required at a number of levels, each having a variety of quality of service requirements for the interaction channel. The interaction channel, often referred to as the return channel, generally includes both upstream and downstream paths, but in some instance
7、s may use only an upstream path to the source of the service. Interactivity can be local only without a return path, or simple interactivity using a unidirectional interaction channel or in its fullest form using a bidirectional interaction channel to and from the source of the service. There is, th
8、us, a need for the harmonization of systems for the provision of interactive services. 2 Scope This Recommendation gives general guidance for a worldwide common family of systems for the provision of interactive television services to the public. It is a preliminary step towards facilitating the int
9、eroperability of interactive services. It is intended to assist in the preparation of future Recommendations for specific services which should take into account the output from other ITU groups, dealing with multimedia services. This Recommendation is based on the following principles: a there shou
10、ld be maximum commonality in the techniques used for interactive television services delivered by HFC, SMATV, MMDS , LMDS, ISDN, ADSL, terrestrial over-air transmission, satellites, etc.; the interaction channel should be designed as a “container able to transport data services (including video, aud
11、io and the associated data signals) in a transparent and flexible way. b) Guidance for harmonizing the development of interactive television services can be found in the service architecture shown below. It is beyond the scope of this Recommendation to specie the technical details of the transport a
12、nd access networks used for media delivery and application interaction. A preliminary list of technical parameters under study which may affect such specifications is provided in informative Appendix I. Bibliography Recommendation J. 1 - Terminology for new services in television and sound-programme
13、 transmission, April 1997. Recommendation J. 83 - Digital multi-programme systems for television, sound and data services for cable distribution, April 1997. Recommendation J.84 - Distribution of digital multi-programme signals for television, sound and data services through SMA TV networks, April 1
14、997. M.3000-series of Recommendations - Telecommunication management network. Recommendation 1.414 - Overview of Recommendations on layer 1 for ISDN and B-ISDN customer accesses. Recommendation ITU-R BO. 1294 - Common functional requirements for the reception of digital multi-programme television em
15、issions by Satellites operating in the 1 li1 2 GHz frequency range. Recommendation ITU-R BT. 1300 - Service multiplex transport and identlfcation methods for digital terrestrial television broadcasting. Recommendation ITU-R BT. 1306 - Error correction, dataframing, modulation and emission methods fo
16、r digital terrestrial television broadcasting. Terms and definitions The terms and definitions in Recommendation J. 1 apply and are augmented by the definitions below for the purposes of this Recommendation. Broadcast channel: A unidirectional, broadband, point-to-multipoint channel, which may inclu
17、de video, audio and data. The broadcast channel is established from the service provider to the users. It may include the forward interaction path. . Interaction channel: A bidirectional channel between the user and the service provider for interaction purposes. In certain implementations the intera
18、ction channel could also carry a user selected broadcast service. In general the interaction channel is formed by: Return interaction path (return channel): A communication channel from the user to the service provider. It is multiple point-to-point. Forward interaction path: An individual communica
19、tions channel from the service provider to the user. It may be embedded into the broadcast channel. This channel may not be present in all implementations. 5 Abbreviations ADSL Asymmetric Digital Subscriber Line GSM HFC Hybrid Fibre Coax ISDN Integrated Services Digital Network LMDS Local Multipoint
20、 Distribution System MMDS Multichannel Multipoint Distribution System SMATV Satellite Master Antenna Television Global Systems for Mobile Communication TMN Telecommunications Management Network. 6 The basic requirement of an interaction channel is that the user be able to respond in some way to the
21、interactive service. This response may take the form of “voting” for a particular participant in a competitor show, “purchasing” goods that are demonstrated or advertised in a shopping channel programme, etc. This would be achievable within a one-way (reverse direction) narrow-band path. A higher le
22、vel of interactivity might require that a user, who has made a response to an interactive service, be sent an acknowledgement. This might be the case where the consumer has made a credit card purchase from a shopping channel via the basic interaction channel. That consumer would expect to receive an
23、 acknowledgement that his or her credit card transaction had been accepted. This level of interactivity would require a two-way interaction channel, one in the reverse direction, the other the forward direction. Interactivity and the role of interaction paths A further level of interactivity would o
24、ccur where in response to information in the interactive service, the consumer requests further information on particular topics from the source of the service, or from a central database via the source of the interactive service. This could require that the forward channel be broadband. In this par
25、ticular example, the reverse path would only need to be a narrow-band one, but it is possible that applications will arise whereby the consumer will need to make a broadband responsecontribution to the interactive service and also receive a broadband “answer” from the service source. 7 Reference mod
26、el for the interaction channel A reference model for the system architecture of a narrow-band interaction channel in a broadcasting scenario is shown. In this reference model, two channels are established between the user and the service provider, as in Figure 1/J. 1 1 O. The detailed reference mode
27、l is presented in Figure 2/J. 1 1 O. STD-ITU-R RECMN BT-13bS-ENGL 1998 = Li855212 0534b85 8Li1 452 8 In Figure 2/J. 1 1 O, the top section represents the unidirectional broadcast channel. This is fully specified by other relevant Recommendations of the ITU (e.g. ITU-T Recommendation 5.83 for HFC, IT
28、U-T Recommendation 5.84 for SMATV, Recommendation ITU-R BO. 1294 for satellite, and Recommendations ITU-R BT. 1300 and ITU-R BT. 1306 for digital terrestrial television). Specification of the broadcast channel FIGURE VJ.110 Illustration of channel terminology in interactive television systems Broadc
29、ast channel Broadcast service provider n Interactive service (i provider Interaction channel Forward interaction path Return interaction path - TO903830-96 FIGURE 2/J. 1 1 O Functional reference model for interactive television services - Transmission network Ao independent ISDNIB-ISDNIADSL Set-Top
30、Box (STB) t-) Transmission network independent TO903840-96 Transmission network physical link STD-ITU-R RECMN BT-13bS-ENGL 1998 4855232 053qbAb 788 D 453 9 The lower part of Figure 2/J. 1 1 O represents the bidirectional interaction channel. Several interfaces exist within the interactive system. Th
31、ese are related to specific areas where it is proposed that standards should be developed. These are: Specification of the interaction channel A,: A,: A, : A,: A,: A,: A,: A, : Set-top unit to interactive interface module. This can be either internal or external to a set-top unit. This interface is
32、network independent. Set-top unit to network interface unit. This can be either internal or external to a set-top unit. This interface is network independent. Interactive interface module to interaction media. This interface is network dependent. Network interface unit to broadcast and interaction m
33、edia. This interface is network dependent. Interaction media to interactive network adaptor. This interface is network dependent. Interaction media and broadcast media to interactive network and broadcast network adaptors. This interface is network dependent. Interactive network adaptor to interacti
34、ve service providers system. This can either be connected directly to a server or via a “core network”. This interface is network independent. Interactive and broadcast network adaptors to interactive service and broadcast service providers systems. This can either be connected directly to a server
35、or via a “core network”. This interface is network independent. The detailed specification of the interfaces at the reference points shown in Figure 2/J. 1 1 O are likely to be the subject of future ITU-T Recommendations. It is expected that the interactive service control used will take advantage o
36、f modern design techniques, such as the use of layered protocols. Where more than one interaction network is required (e.g. SMATV to VSAT) several interaction media to interaction media interfaces may be used in series. Where the broadcast channel and the interaction channel are carried over the sam
37、e medium, A4 and A, could be combined as a common interface and also Al and Ab could be common. 9.1 Interaction channel transport mechanisms The interaction channel is an integral part of the interactive television system. This is the portion that will allow the home viewer to respond and interact w
38、ith the information contained in the service. In principal, a number of possibilities exist for the interaction channel: - in over-the-air applications, it may be possible to use the existing receiving antenna and cable. It may also be possible that a special transmitterreceiver unit could be incorp
39、orated into the television set. It is also possible that a simple transmitter and antenna, similar to those used for cellular mobile systems, may be a more cost effective solution; use of existing cable systems, by utilizing the return channel capability of the cable systems or of SMATV systems; the
40、 use of satellite-based systems such as VSAT, to link the nodes which concentrate the signals from a number of different users to a service provider; - - - a simplified version of mobile telephone equipment, using the same cellular stations as the mobile service, or possibly using separate receiving
41、 stations located at the television transmitter. In the case of using the same cellular mobile stations, a more simplified version of the data transmission protocol may be used; use of the existing public telephone (telecommunications) networks, including ISDN/B-ISDN/ADSL (see ITU-T Recommendation 1
42、.414); a similar solution may be possible by using mobile service via low-Earth orbit satellites (LEOS); - - - use of the Internet. 9.2 Interaction channel characteristics 9.2.1 Data rate The preliminary studies for the return interaction path user bit rates have been grouped into three categories:
43、a Low data rate (L), implies a data rate of approximately 150 bit/s, or even less, for simple return commands, including simple error correction. b) Medium data rate (M), implies a data rate of approximately 6 to 7 kbits/s for more complex applications and instructions, including the requirement for
44、 more sophisticated protection for security and error protection coding. High data rate (H), implies a data rate of typically 64 kbitsh, or more, and possibly up to several Mbits for more demanding applications. c 9.2.2 Bandwidth In many cases bandwidth will depend not only on data rate, but also on
45、 the specific choice of transport mechanism and frequency band. In any over-the-air applications, the system parameters will most likely 0110 the bandwidth parameters of the systems already in mass production. For example, where it is proposed to use the existing cellular mobile network, some of the
46、 main parameters of that mobile system may well be appropriate to the interaction channel. 9.2.3 Modulation The modulation and coding will depend mainly on the system used for the interaction channel, and should be selected, if possible, from existing methods so as to utilize mass produced component
47、s, particularly where more expensive solutions are proposed for the interaction channel. 9.2.4 To ensure openness of access for users and services and of maximum commonality among interactive services and customer premises equipment, the protocols and interfaces used in the interaction path should b
48、e common, open and standardized. Similarly, the protocols should be arranged in layers, independent of each other to the extent possible, to enable future development. Structure of the interactive service 10 Management functions For further study. It is expected that any Recommendations will be cons
49、istent with TMN principles, as documented in the ITU-T M.3000-series of Recommendations. STD-ITU-R RECMN BT-13bS-ENGL 1778 H i855212 0534b88 550 455 APPENDIX I (to Recommendation J. 1 1 O) Technical parameters under study A number of technical parameters are still under study which may affect the detailed specification of the access and transport network interfaces. These include: a channel delay; b) duty cycle; cl reception (fixed and mobile); d) 4 f) SI h) data flow control; i) quality of service; j flexibility; k) potential interference impact to or from other services; 1) int
